The field of the present invention is infusion systems.
Today, diabetes is understood to be reaching epidemic proportions in the United States. It remains as a worldwide problem as well. Diabetes brings with it a host of medical problems which are aggravated by conventional medicament dosage schemes. Traditional shots and the like are intermittent which can induce a cyclical plethora and paucity of medicament, typically insulin. Recent efforts have been undertaken to eliminate such harmful cyclical variations through continuous administration of medicament. Additionally, devices and controls have been designed to provide both a basal rate for sustained infusion and periodic boluses to accommodate the ingestion of carbohydrates. With these advantageous capabilities, enhanced designs taking into account considerations regarding cost, portability, longevity and accuracy of dispensation remain of interest.
A wide variety of prior systems having applicable components and processes exist. Reference is made to U.S. Pat. Nos. 4,898,578; 5,205,819; 5,630,710; 6,645,142; 6,852,104; and 7,018,360. Reference is also made to U.S. Patent Publications Nos. 2002/0029776; 2003/0032867; 2003/0163088; 2004/0220551; and 2005/0137573. The disclosures of the foregoing patents and patent publications are incorporated herein by reference.
In addition to the infusion of insulin for diabetes, infusion is useful for other purposes in bodies of both humans and animals. The types of liquids that can be delivered include, but are not limited to, insulin, antibiotics, nutritional fluids, total parenteral nutrition or TPN, analgesics, morphine, hormones or hormonal drugs, gene therapy drugs, anticoagulants, analgesics, cardiovascular medications, AZT and chemotherapeutics. The types of medical conditions treatable by infusion include, but are not limited to, diabetes, cardiovascular disease, pain, chronic pain, cancer, AIDS, neurological diseases, Alzheimer's Disease, ALS, Hepatitis, Parkinson's Disease or spasticity.
Infused patients have increased mobility with portable infusion dispensing systems while achieving a more frequent or continuous dosing. Such systems have the potential for regulating dosing responsive to near term need and conditions, such as the intake of carbohydrates in the case of diabetes. Control of the dispensing process to achieve accurate dosing is a fundamental design criteria for such devices. Various approaches have been used to control pump parameters and flow with piezoelectric mechanisms. U.S. Pat. No. 6,986,649 uses valve control based on pressure. U.S. Pat. No. 7,258,253 uses a restrictive orifice. U.S. Pat. No. 7,290,993 uses electronic wave form control. The disclosures of these patents are incorporated herein by reference. Control and monitoring of piezoelectric systems accurately enough for infusion demands more than electronic input and needs performance feedback. Simple, reliable and inexpensive miniaturized systems not having expensive critical components and system complications remain advantageous.
Also of consideration with portable infusion dispensing systems is patient comfort. Such systems frequently require subcutaneous cannula. The solution has been to make the cannula of flexible material and use a rigid sharp pin through the cannula to place the device, then withdrawing the pin. Rigid cannula are less complicated to place but can induce discomfort with patient movement.